The radio device utilizing a short range radio can replace a general mobile device utilizing a long range radio. The method that allows a message to be transmitted from its source radio device to a target radio device is by forwarding the message to other radio devices the source encounters. These radio devices further forward the message to other radio devices they encounter opportunistically until the message reaches the target radio device. This way, users don't need to pay the telecommunication charges sending data messages in area where there are frequent radio device encounters.
In the past, to increase the usage time of the radio devices, the duty cycle of the radio device may have been controlled by some method. One of the operation times would be set as the “on state” and the other operation time would be set as the “off state” during the duty cycle of the radio device. For example, if the duty cycle of the radio device were one minute, the front 10 seconds of the duty cycle would have been set as the “on state” and the back 50 seconds of the duty cycle would have been set as the “off state.” Therefore, the power consumption of the radio device would be reduced by decreasing the time needed for the radio device to be on, so that the usage time of the radio device could be prolonged.
However, if the radio device is turned on/off periodically, following problems arise.
For example, if a radio device needs to exchange a data message with another device in its vicinity, but has been turned off by the periodic on-off method, it will be unable to perform the data exchange.
On the other hand, a radio device being turned on by the periodic on-off method can perform a data exchange, but there may be no other radio device in its vicinity. As a result, the power of the radio device would be wasted.
Furthermore, when the radio device exchanges a data message with a neighboring radio device, the radio device may suddenly be turned off by the periodic on-off method, resulting in failure for the data exchange.
Therefore, how to provide a power switch mechanism suitable for the conditions under which the radio device will be used, so that the radio device can achieve efficiency in saving power and smoothly exchange data messages with other radio devices, is the object to be achieved by the present invention.